• Journal of Power System Engineering
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• v.10 no.4
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• pp.31-37
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• 2006

In this study, the ability for the function of double pipe inserted liquid pipe with small diameter in the gas pipe with large diameter for the circulating of liquid of high temperature and high pressure and low temperature and low pressure at the same time is presented. And in this double pipe, liquid pipe of high temperature and pressure is used to connect condenser and expansion valve and gas pipe of low temperature is used to connect evaporator and compressor. Also, when liquid refrigerant of high temperature and gas refrigerant of low temperature is circulated by reversed flow in the double pipe. The contribution of liquid gas heat exchange pipe is studied by comparison of the effect of heat transfer by temperature difference when liquid pipe and gas pipe is installed separately.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.421-426
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• 2005

For the air-conditioner, refrigerant induced noise and vibration should be the problem when it reduced airflow rate in order to reduce the noise at low mode. With the test, it could be verified that one of the main reason for refrigerant induced noise were the velocity and flowing induced force of the refrigerant at the inlet of evaporator. So in order to reduce this velocity with same mass flow rate of refrigerant, quality at the evaporator inlet should be minimized. And in order to reduce flowing induced force of the refrigerant, flowing direction change should be eliminated. So in this paper, it would like to review the characteristics of refrigerating cycle at first and find how the quality and flowing induced force can be minimized.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.6
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• pp.86-95
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• 2002

This paper suggests the new technology to control metal flow in order to reduce the number of preforming and the machining for the cold forged product with complex geometry. This technology is the combined forming that consists of bulk and sheet forming with double action dies. To analyze the process, finite element simulation has been performed. The proposed technology is applied to hub model that is part of air conditioner clutch. The purpose of this study is to investigate the material now of hub through the relative-velocity control of punch and mandrel using the flow control forming technique.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.9
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• pp.952-960
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• 2008

Fan noise prediction method is presented for air conditioning, automobile and electronic cooling system applications where fan acts as an internal equipment having very complicated flow interaction with other various system components. The internal flow paths and distribution in the fan-applied systems such as computer or air conditioner are analyzed by using the FNM(flow network modeling). Fan noise prediction method comprises two models for the discrete frequency noise due to rotating steady aerodynamic lift and blade interaction and for the broadband noise due to turbulent boundary layer and wake vortex shedding. Based on the fan operation point predicted from the FNM analysis results and fan design parameters, the present far noise model predicts overall sound pressure level and spectrum. The predictions for the flow distribution, the fan operation and the noise level in air cooling system by the present method are well agreed with 3-D CFD and actual noise test results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.2
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• pp.87-93
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• 2009

Slim telecommunication cabinet cooler, equipped with parallel flow heat exchangers and operating with R-22, is developed. The performance is compared with imported one, equipped with fin-tube heat exchangers and operating with R-134a. Test results show that the newly-developed cooler increases the cooling capacity by 6% and EER by 33%. The refrigerant charge for the developed cooler is 500g compared with 1250g for the imported one. The adoption of parallel flow heat exchanger appears to have reduced the refrigerant charge. In addition, it is shown that the reduced air flow rates through parallel heat exchangers as compared with those through fin-tube heat exchangers are beneficial to the reduction of the equipment noise.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.538-543
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• 2000

DS(Differentiated Service)에서는 RSVP와 같이 개별 flow에 대한 QoS제공이 아닌 flow들의 집합(aggregate)으로 차등적인 서비스를 제공하는 방법이다. 확장성을 고려한 이러한 방안은 광역백본망 에서와 같이 수천, 수만의 flow들에 대해 서비스를 제공하고자 할때 flow들을 집합(aggregate)화 하여 차등적인 서비스를 제공하고자 하는 것은 매우 큰 의미가 있다고 할 수 있다. 하지만 DS에서는 Token Bucket 방법을 사용하여 트래픽 스트림을 측정하는 이유로 불특정 flow에 대해 심각한 QoS손실을 야기할 수 있다. 본 논문에서는 자원공유의 공정성을 기여하기 위해 Traffic Conditioner에서 사전 모니터링 방법을 사용하고 이 모니터링 결과를 Weighted Fair Queuing의 파라메터로 사용하여 잉여 자원을 효율적으로 사용하는 방안을 제시한다.

• Journal of Power System Engineering
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• v.16 no.3
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• pp.29-36
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• 2012

The computational flow analysis using LES technique was introduced to investigate the flow field improvement of an indoor RAC chassis consisting of a rear-guider, a stabilizer and a cross-flow fan. This unsteady three-dimensional numerical analysis was carried out by the commercial SC/Tetra software. The edge blocks were adopted in this study as a tool for the flow field improvement of an indoor RAC. In view of the results so far achieved, the edge blocks cause the center of an eccentric vortex to be stable along all length of a cross-flow fan, and then, the static pressure and the velocity vector show a stable distributions. In consequence, because the edge blocks eliminate a reverse flow near the edges, an exhausting flow becomes to be stable and uniform.

• The KSFM Journal of Fluid Machinery
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• v.2 no.1 s.2
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• pp.96-102
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• 1999

Cross flow fans are used in various applications, especially in industrial ventilation applications and in room air conditioners, due to their superior performance characteristics. Unlike radial and/or axial fans, the design of cross flow fans have been mostly based on earlier experiences and experiments. In the present study, numerical computations of flow fields through a cross flow fan used in room air conditioner are performed to investigate the detailed flow fields and to study the effect of the blade shape on performance curves to aid better design of the fan. Despite some discrepancies between the two results, it is seen from the present study that the computational results agree quite well with the qualitative experimental results. It is also shown from the present study that by having a different shape of blade, it is possible to achieve about $15\%$ increase in flow rates. The stimulating results of the present study can be used in the design of high performance cross flow fans with the use of optimal design algorithm and experimental verifications.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.594-601
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• 1997

Propeller fans are commonly equipped in outdoor units of air-conditioners to provide effective cooling in a dried heat exchanger. A new design technique was developed to satisfy requirements of aerodynamic and aeroacoustic performance, which employs the intersection method of two cylinders for mean camber line. Three proto-types of propeller fan including Palm-Shaped, Highly-Swept(PSHS) fan (proto 3)were not only to provide low lift forces for dipole sound, but also to reduce the organized tip vortices interacting with the fan guide causing narrow-banded rotating instabilities. Cross-correlation technique was applied to study flow noise source characteristics for three proto-type fans designed. The cross-correlations between a microphone at far field and a hot-wire sensor at near field show that flows near hub region of proto 3 fan are less organized and the flow structures especially at high flow rate coefficients for proto 3 fan are less correlated with noise generated than other proto-types fans.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.78-82
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• 2004

The cross-flow fan which is used for air-conditioner indoor units were studied experimentally. The recent trend shows that the room air-conditioners need to be good-looking. According to the visual design concepts the intake regions of the fan can vary, which leads to the loss of the performance and the increase of the noise of the fan. In order to optimize the performance of the fan and minimize the aerodynamic noise for the system, the performance characteristics and the noise of the cross-flow fan have been investigated at the various conditions of the intake region of the unit.